chomp_cost.cpp
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00034 
00035 /* Author: Mrinal Kalakrishnan */
00036 
00037 #include <chomp_motion_planner/chomp_cost.h>
00038 #include <chomp_motion_planner/chomp_utils.h>
00039 #include <eigen3/Eigen/LU>
00040 
00041 using namespace Eigen;
00042 using namespace std;
00043 
00044 namespace chomp
00045 {
00046 ChompCost::ChompCost(const ChompTrajectory& trajectory, int joint_number, const std::vector<double>& derivative_costs,
00047                      double ridge_factor)
00048 {
00049   int num_vars_all = trajectory.getNumPoints();
00050   int num_vars_free = num_vars_all - 2 * (DIFF_RULE_LENGTH - 1);
00051   MatrixXd diff_matrix = MatrixXd::Zero(num_vars_all, num_vars_all);
00052   quad_cost_full_ = MatrixXd::Zero(num_vars_all, num_vars_all);
00053 
00054   // construct the quad cost for all variables, as a sum of squared differentiation matrices
00055   double multiplier = 1.0;
00056   for (unsigned int i = 0; i < derivative_costs.size(); i++)
00057   {
00058     multiplier *= trajectory.getDiscretization();
00059     diff_matrix = getDiffMatrix(num_vars_all, &DIFF_RULES[i][0]);
00060     quad_cost_full_ += (derivative_costs[i] * multiplier) * (diff_matrix.transpose() * diff_matrix);
00061   }
00062   quad_cost_full_ += MatrixXd::Identity(num_vars_all, num_vars_all) * ridge_factor;
00063 
00064   // extract the quad cost just for the free variables:
00065   quad_cost_ = quad_cost_full_.block(DIFF_RULE_LENGTH - 1, DIFF_RULE_LENGTH - 1, num_vars_free, num_vars_free);
00066 
00067   // invert the matrix:
00068   quad_cost_inv_ = quad_cost_.inverse();
00069 
00070   // cout << quad_cost_inv_ << endl;
00071 }
00072 
00073 Eigen::MatrixXd ChompCost::getDiffMatrix(int size, const double* diff_rule) const
00074 {
00075   MatrixXd matrix = MatrixXd::Zero(size, size);
00076   for (int i = 0; i < size; i++)
00077   {
00078     for (int j = -DIFF_RULE_LENGTH / 2; j <= DIFF_RULE_LENGTH / 2; j++)
00079     {
00080       int index = i + j;
00081       if (index < 0)
00082         continue;
00083       if (index >= size)
00084         continue;
00085       matrix(i, index) = diff_rule[j + DIFF_RULE_LENGTH / 2];
00086     }
00087   }
00088   return matrix;
00089 }
00090 
00091 double ChompCost::getMaxQuadCostInvValue() const
00092 {
00093   return quad_cost_inv_.maxCoeff();
00094 }
00095 
00096 void ChompCost::scale(double scale)
00097 {
00098   double inv_scale = 1.0 / scale;
00099   quad_cost_inv_ *= inv_scale;
00100   quad_cost_ *= scale;
00101   quad_cost_full_ *= scale;
00102 }
00103 
00104 ChompCost::~ChompCost()
00105 {
00106 }
00107 }


chomp_motion_planner
Author(s): Gil Jones
autogenerated on Mon Jul 24 2017 02:21:07